An SC-FDMA (Single Carrier Frequency Division Multiple Access) system as an example of a signal transmission system in digital radio communication can realize high transmission power efficiency and high frequency usage efficiency. In general, a transmitter that performs signal transmission using the SC-FDMA system has a function of performing discrete Fourier transform and inverse discrete Fourier transform. First, the discrete Fourier transform is executed on a transmission signal symbol sequence to create frequency domain data of a transmission symbol sequence. Thereafter, the frequency domain data of the transmission symbol sequence is allocated to a predetermined frequency in a system band. The inverse discrete Fourier transform is applied to a result of the allocation to create an SC-FDMA transmission signal.
In recent years, as a method as expansion of the SC-FDMA system, a technology having a plurality of SC-FDMA transmission systems corresponding to different frequency bands in one transmitter is disclosed (see, for example, Non Patent Literature 1 described below). In this technology, it is possible to deal with a wideband system by combining SC-FDMA transmission signals generated by the respective SC-FDMA transmission systems and transmitting this combined signal. The technology is disclosed in, for example, Non Patent Literature 1 described below.    Non Patent Literature 1: Nokia Siemens Networks, Nokia, “R1-082609: Uplink Multiple Access for LTE-Advanced”, 3GPP TSG RAN WG1 Meeting #53bis Warsaw, Poland, Jun. 30-Jul. 4, 2008.